Concrete delivery pipeline failures

Background

Concrete delivery pipelines are used on various types of concrete pumping equipment (such as mobile / tower concrete placing boom pumps and line pumps) to deliver pressurised concrete from the pump to the concrete pour location. Pipelines can be made up of several components including pipes, reducers, bends, hoses and couplings.

Pipeline failures can expose employees, other site workers and members of the public to the risk of being struck by high pressure concrete or metal debris which potentially could result in death or serious injury.

Poorly manufactured pipes have been a contributing factor in a number of incidents involving the rupture of concrete delivery pipelines and escape of pressurised concrete.

Defects have been identified both in imported complete pipes and in pipes manufactured locally from separate components. Defective pipes have also been found on preassembled boom pumps.

Employer duties and recommended control measures

Employers have specific duties in relation to plant under the Occupational Health and Safety Act 2004 and Occupational Health and Safety Regulations 2007. Employers must provide and maintain plant that, so far as is reasonably practicable, is safe and without risks to health.

An employer or self-employed person must, so far as is reasonably practicable, identify all hazards to health and safety associated with the installation and use of plant. They must also ensure that any risk associated with plant is controlled so far as is reasonably practicable.

The quality of pipes and pipeline components may vary between batches, therefore solely relying on the supplier's quality assurance accreditation, test reports or mill certificates may not ensure that pipes and components are safe for use.

Prior to putting concrete delivery pipes and associated pipeline components into service they should be inspected to confirm that they have been designed and manufactured appropriately, this includes inspecting for:

• defective welds
• misaligned welded components
• poorly manufactured pipeline restraint/weld rings that are irregular in size and shape
• inadequate restraint/weld ring grooves which can lead to a lack of contact with the next pipe in the pipeline and/or coupling
• porosities in the metal created by the cold drawing manufacturing process that may lead to cracks developing.

Employers and self-employed persons must ensure that plant is inspected to the extent necessary to ensure that risks associated with its use are monitored. Regular inspection and testing should be undertaken to ensure that concrete delivery pipelines are safe and without risk to health, this may include inspection and testing by an independent third party. Note: the quality of pipes and pipeline components may vary over time between batches from the same supplier.

Employers must provide such information, instruction, training or supervision to employees to enable those persons to perform their work in a way that is safe and without risks to health, this includes training on identifying pipe and pipeline component defects.

If issues are identified with pipes and pipeline components they should be taken out of service until appropriate testing has been undertaken. This may include destructive, non-destructive, pressure, cyclic, or hardness testing to confirm that pipes and pipeline components perform in accordance with their original design and will not fail under the maximum rated pipeline pressure (for more information see AS4041 – Pressure piping).

Failed pipes or pipeline components must not be used until they are repaired or alternatively they should be destroyed.

When welding pipeline components, a competent person should be engaged to produce a welding specification and welding procedure. The welder performing the required weld should be competent to do so, as welding hardened steel incorrectly can lead to issues such as brittleness. A weld inspection should also be undertaken by a competent person to ensure that the weld meets the original welding specification.

Other publications

• AS2550.15 - Cranes, hoists & winches - Safe use - concrete placing equipment
• AS1418.15 - Cranes (including hoists and winches) - concrete placing equipment
• AS4041 - Pressure piping.